Various designs of vacuum cleaner have been developed over the years. The conventional cleaner draws dust laden air through a cloth or paper container in which all particles larger than the pore size of the material forming the wall of the container, will be retained.
Finer particles will pass through the porous wall and one or more filters are provided prior to the source of vacuum (usually an electrically powered motor driven fan or turbine), to trap these fine particles and prevent them being recirculated into the environment from which they have been removed by suction in the first place.
These filters will eventually become clogged and have to be cleaned and/or replaced. Long before that stage is reached however, the partial clogging of the filter(s) will reduce